1. Field of the Invention
The invention relates to articles of manufacture which are adapted to be electrically welded to a supporting structure, the method of construction of such articles and the method of welding the articles to a supporting structure, particularly articles having a synthetic thermoplastic substructure and an external metallic plating on the substructure.
2. Description of the Prior Art
The subject matter of this disclosure is considered to have application in various of the industrial arts including but not limited to the manufacture of automotive vehicles, business and domestic appliances, electronic data processing equipment, and many others, some of which remain unforeseen at this time. However, it would appear to be important that those who would subsequently employ the teachings of the disclosure understand that the principal motivating force behind the development of the product and processes disclosed was the recognition of a need in the automobile industry for an improved method and a product adapted for application by the method which would result in more efficient and less expensive procedures for attaching ornamental devices, articles of indicia, moldings, etc. (all of which can be generally classified as "trim") to exterior body panelling.
In the art of trim attachment it has long been the practice to employ various fastening means including screws, bolts and nuts to secure the trim to perforated body paneling. Snap fasteners of various types have also been utilized with apertured panels.
More recently, with a view to eliminating perforation of the paneling, so-called "no-hole" fastening systems have been introduced to the art. The basic component of the best known and most widely used of these systems is a very small, headed stud which is welded (usually by arc welding or so-called "capacitor discharge" welding) to an exterior body panel either before or after painting and finishing of the panel. A separate adapter, which is usually of either spring metal or resilient synthetic plastic construction is utilized as the coupling member for securing trim to the welded stud. Depending on the type of adapter utilized, it may be preassembled with the trim and that subassembly later engaged with the stud, for example, by snapping the adapter over the stud head, or in the alternative by first attaching the adapter to the stud and thereafter snap engaging the trim and the adapter.
Trim formed from various sheet or die-cast metals has been secured by the aforementioned fastening methods and systems, and I am aware of experimental attempts to weld sheet metal of die-cast trim directly to body panelling, absent the utilization of specific welding elements in conjunction with such trim; but I am not aware that the latter approach to the problem has ever provided a solution which was considered satisfactory for commercial implementation.
The last decade has seen the development and perfection of a number of processes for applying decorative metallic plating to molded and extruded synthetic plastic parts. For a number of reasons including reduced weight and cost, the automotive and appliance industries have replaced sheet and die-cast trim in both internal and external installations with plated plastic trim. In automobiles such parts are used internally as outliners for instrument clusters, control knobs, door handles, door lock knobs, identification logos, coat hooks, etc. Externally, plated plastic trim has replaced sheet and die-cast metallic parts for decorative moldings, model and manufacturers identification names and symbols, dealer advertizing plates, etc. However, there has been no substantial advance in the art of fastening external trim in that screws, bolts and nuts, snap fasteners, no-hole studs and adapters and adhesives continue to be utilized to attach the plated plastic trim in much the same manner and degree as those systems and methods were used with sheet and die-cast metal trim. It is not the intention of the foregoing remarks to convey the impression that the aforementioned fastening methods and systems are totally without merit, but it is significant to note that each has certain disadvantages and deficiencies, the elimination of which constituted the challenge which motivated and gave impetus to the improvements in the art disclosed herein.
The disadvantages of utilizing screws, nuts and bolts, snap fasteners or other fastening means which required the prepunching of fastener receiving holes in body panelling are elaborated upon in considerable detail in U.S. Pat. Nos. 3,153,468 and 3,188,731 to which reference may be had. The above mentioned patents and U.S. Pat. No. 3,340,379 relate to the earlier mentioned no-hole fastening systems and the inventions disclosed therein are quite generally recognized as having made a definite contribution to the art of trim attachment. However, it is a principal object of the present invention to advance the art still further by providing a more efficient and less costly system, as well as a system which encourages greater utilization of metallically plated plastic trim, both internally and externally in dynamic as well as static installations. To that end the present invention: (a) eliminates the need for the various special adapters which are characteristic of the known no-hole systems; (b) permits the attachments of decorative trim at the most opportune time in an automotive mass production cycle; (c) simplifies trim attachment in that the piece and welding element constitute a unit which is simultaneously secured to the body panelling; (d) reduces the cost of installation equipment in that multiple welding heads arranged in various predetermined patterns for the premounting of studs are no longer required; (e) provides a system wherein special sealing components for corrosion prevention in the area of the weld are no longer required; (f) contributes to a simplification of the manufacturer's inventory control and material flow systems in that the problems inherent in insuring that particular panelling having the requisite number of preattached studs in the desired predetermined pattern are consistently available at the trim installation station of a production line are substantially reduced; and (g) provides for the rapid attachment of trim to finished (e.g. painted) panelling in a manner which satifies industry's standards relative to ultimate strength and durability in the fastening, protection against corrosion and over-all attractiveness of the assembly.
Additional improvements which the invention contributes to the art of trim attachment will become evident from a consideration of the detailed description of the invention which follows hereafter in conjunction with a viewing of the accompanying drawing.